The vitellogenin gene(s) of the mosquito Aedes aegypti will be cloned using methods that capitalize on the fact that vitellogenin, the precursor to yolk protein, is found only in females. The vitellogenin-specific DNA probes that are obtained will be used to answer several important questions: How is the expression of the vitellogenin gene regulated by juvenile hormone and ecdysterone? How many vitellogenin genes are there, and if multiple, are they coordinately expressed? How are the vitellogenin genes arranged on the chromosome? Obtaining answers to these questions will be a significant step towards understanding how hormones regulate egg development in these medically important insects. These studies will contribute to our understanding of how hormones control protein synthesis, and will give some insight into the organization and expression of the vitellogenin gene(s).